Traditionally, such an electromechanical actuator comprises an actuator, typically a rod, which, by translation, deploys and retracts with respect to a case of the actuator, under the driving action of an electric motor supported by the case. A transmission connects the output of the motor, often rotating, to the end of the rod, opposite that deployed outside the case. In practice, during various maneuvers by the aircraft, the actuator is implemented in harsh environments, in which it is subject to liquid water, steam, oxygen from the air, dust, dirty spray, sand, etc., which, over time, tend to alter the operation of its actuator by corroding the electric motor and/or the transmission, as well as by attenuating their lubrication. To protect the motor and the transmission, it may be provided to arrange them in an inner volume of the case, but this solution quickly proves ineffective inasmuch as, by closing this inner volume, a relative vacuum is created therein when the rod is deployed outside the center volume, such that the corrosion agents listed above tend to penetrate therein easily, by aspiration and/or driving by the rod during the retraction of the latter: once these agents have penetrated the inside of the inner volume of the case, they alter the operation of the actuator, in the same way as when there are no arrangements related to the aforementioned inner volume.